Paint Layers Research Articles

New Perspectives for the Consolidation of Mural Paintings in Hypogea with an Innovative Aqueous Nanolime Dispersion, Characterized by Compatible, Sustainable, and Eco-Friendly Features

Consolidation of mural paintings in hypogea is challenging because of their severe microclimatic conditions, characterized by high humidity levels, low air circulation, the presence of salts efflorescence, and the detrimental growth of biodeteriogen agents. Traditional consolidant products show significant drawbacks when used in hypogeum. Organic compounds, such as acrylic emulsions, are bio-receptive and some inorganic consolidants, such as silica-based products, show a lack of compatibility with the original substrate, which could lead to a reduction in permeability and an increase in the mechanical resistance of the external layer. The presence of solvents in their formulations, particularly short-chain alcohols that can activate germination of fungal spores, leads to the release of great amounts of volatile organic compounds, which are particularly harmful in the hypogeic environment. To solve these problems, restorers of the Istituto Centrale per il Restauro (ICR) decided to use a new aqueous nanolime dispersion, NANOLAQ, consisting of pure and crystalline Ca(OH)2 nanoparticles dispersed in water, produced by an innovative and sustainable patented procedure. After laboratory testing, the product has been applied on site, on a medieval mural painting in the Ss. Peter and Paul hypogeum in the UNESCO site of Matera (Italy), monitoring the performance in terms of cohesion of the paint layer and preservation of aesthetic features.

Complex coating system for improving corrosion resistance of AZ31 magnesium alloy

Complex coating for corrosion protection was developed on magnesium alloy AZ31 using plasma electrolytic oxidation (PEO), spray pyrolysis (SP) and two-part paint. PEO coatings were obtained using electrolyte with phosphate modifier. The oxide layer formed via PEO was sealed using pyrolyzed TiO2 and finally coated with spray primer-paint system to further protect the surface. The specimens were tested for corrosion using immersion gravimetric method in 3% NaCl solution for 1 week and mass loss was recorded. Morphology of the PEO and SP coatings were studied using SEM and chemical analysis of SP coating by EDS. It was found that 30 minutes of spray time in SP process caused surface cracks in the coating. Paint was applied in varying numbers of primer and paint layers and 2 layers each produced the best results in terms of corrosion resistance.

Ikonografija starozavetnih proroka i Bogorodice Kiriotise na istočnom zidu gračaničkog eksonarteksa

The exonarthex of Gračanica has a rich and complex painted programme, which is a testimony to the medieval kingdom of Serbia ruled by the Nemanjić dynasty, after the arrival of the Ottomans in the Serbian regions. This painted programme has been preserved to a certain extent to this day, although the traces of the ravages of time are clearly visible; it is still possible to read and reconstruct the entire thematic programme, as well as to recognise the iconographic and stylistic features of this part of the church. The exonarthex was painted out several times, as it was repeatedly damaged during the turbulent and destructive centuries (14th, 15th, 16th). It was probably fresco painted after its construction (probably around 1330), but there are no physical remains or written sources testifying to this, while today two layers of fresco paintings are clearly visible in the Gračanica exonarthex. The iconography and themes of the younger layer of fresco paintings from 1570 form a more complex and intricate unity in relation to the one that was there originally. The new frescoes have a clear theological background, devotion to the Virgin Mary, who was also the patron of the Gračanica church. The depiction of the cycle of the Virgin celebrates the role of the Virgin in the Incarnation, foretold in prophetic visions. Almost the entire painted programme around the east portal of the Gračanica exonarthex is dedicated to the Mother of God; additionally, some related depictions are shown there, like the Mother of God on the throne with Christ Emmanuel on her lap surrounded by archangels in the lunette above the entrance. The entire composition was introduced with the theme "From above the prophets have prophesied thee", as shown by the painted busts of six prophets (Isaiah, Solomon, David, Moses, Aaron and Jeremiah) entwined by a decorative vine on the inside of the arch, at the top of which is a waist-high image of Christ giving blessings with both hands. The main aim of this paper is to point out the importance of the restoration and painting of Serbian monasteries during the Ottoman rule since these topics are insufficiently represented in Serbian art history. The paper provides an iconographic analysis of the scenes dedicated to the celebration of the Virgin in the Gračanica exonartex, as well as their theological background.

Iconography of the Baptism scene developed from an older layer of fresco painting from around 1530 in the Gračanica monastery exonarthex

Iconography of the Baptism scene developed from an older layer of fresco painting from around 1530 in the Gračanica monastery exonarthex

THE USE OF SUPERSONIC ELECTRIC ARC METALLIZATION TO PRODUCE CORROSION-RESISTANT COATINGS OF AGRICULTURAL MACHINERY PARTS

During seasonal work, as practice shows, the paintwork is subject to damage, which leads to the appearance of corrosion foci on steel structures, the removal of which requires considerable labor. The applied paint coatings of agricultural machinery are short-lived, therefore, the development and implementation of new progressive methods of protecting parts of agricultural machinery from corrosion is important. (Research purpose) The research purpose is to extend the service life of agricultural machinery by creating an anticorrosive coating by supersonic electric arc metallization with subsequent application of paint and varnish coating. (Materials and methods) Abrasive blasting with corundum was performed for preliminary preparation of the surface of the parts before coating by electric arc metallization. A specialized installation for electric arc supersonic metallization «Dragon» was used for coating, zinc-aluminum wire Zn85/Al15 was used as the applied material. (Results and discussion) Selected equipment for the preparation of parts and assemblies and the application of anticorrosive coating by supersonic electric arc metallization. We have completed the layout of the site for coating. The modes of supersonic electric arc metallization were established. The modes of obtaining high-quality and durable coating of products were worked out on the basis of the Kaluga Region state enterprise «Kaluga Machine-Technological Station». (Conclusions) Anticorrosive treatment of products operating in aggressive environments is most effective when two coatings are applied sequentially: anti-corrosion layer by electric arc metallization and subsequent application of a layer of paint and varnish coating. The use of the technology of abrasive blasting and anticorrosive protection of housing and frame structures of agricultural machinery by the method of supersonic electric arc metallization allows extending the service life of these structures for 12 years.

Controllability of Laser Removal of Aircraft Skin Paint Layer Based on Response Surface Analysis

Controllability of Laser Removal of Aircraft Skin Paint Layer Based on Response Surface Analysis

Effect of y-direction Overlap Rate on Laser Cleaning of Composite Paint Layer on Aluminum Alloy Surface

Effect of y-direction Overlap Rate on Laser Cleaning of Composite Paint Layer on Aluminum Alloy Surface

Lapis Lazuli Particles on the Turin Shroud: Microscopic Optical Studies and SEM-EDX Analyses

We have studied by optical microscopy and SEM-EDX lapis lazuli particles adhering to a sample of the Turin Shroud. A total number of seventy lapis lazuli particles (and sub-particles) were found on the surface of this sample, and were characterized in details: they are little particles (of between 0.1 and 15 μm of maximal length), of blue colour, and with a spectrum of chemical elements identical to that of the lapis Lazuli mineral. We hypothetise that these particles are residues of painting layers of lapis lazuli that covered initially the Turin Shroud.

Development of Battery Materials to Function as Corrosion Protection on Car Body Plates

Most car bodies made for mass production are made from steel or aluminum. Both are strong metals, but steel is cheaper than aluminum and is more commonly used in lower-end cars for a broader consumer range. The weakness of steel compared to aluminum is that it is susceptible to corrosion under certain conditions, and thus it may deteriorate over time without proper care. To prevent corrosion, modern cars are coated with paint to prevent direct contact with the environment. As a second line of protection, a car battery can be connected to the body to create an impressed current cathodic protection circuit. In this study, a steel sample from the car body is connected to an ICCP or impressed current cathodic protection circuit with a small 12v battery and a graphite anode. The specimen's paint layers are removed through grinding and tested in water, wet soil, and open air. The specimens in water and wet soil experienced minimum corrosion during the testing period, while the ones in open air experienced significant corrosion products on the surface. Overall, due to the small specimen size compared to battery output, all specimens experience a case of overprotection of up to -5516 mv in wet soil and -2666 mv in water. Due to limitations, we are unable to do proper measurements in the open-air environment.

Spectroscopic analysis for evaluation the nano silica as an inorganic and hybrid nano material in treatment of red cinnabar pigment – Based on case study at the Grand Egyptian Museum

One of the most important funerary objects during ancient Egyptian history was the canopic chests, which varied in shape and objective during different ages. Part of a painted wooden canopic chest which dated between the late 27th dynasty (525 BC - 404 BC) to the Greco-Roman period and stored now at the storage rooms of the Grand Egyptian Museum in Giza, Egypt; used as a case study to do an experimental study through designing mimic samples to the object structure, which mainly was wooden support of Ficus Sycamore wood species, covered with white preparation layer of Calcium Carbonates (CaCo3), with a variety of colors for the painting layer; but in our research we concentrate on the red pigment which has been identified as Cinnabar, which from its conservation state was suffering from darkening, cracks, microcracks, and fragility. The experimental study conducted mainly to evaluate the performance of the nano silica for the treatment of the red cinnabar pigment as a consolidation material in two different forms: the inorganic and hybrid; in the inorganic form the nano silica has been dispersed in 2-propanol organic solvent, and its hybrid form the nano silica dispersed in Klucel E organic polymer. and to get accurate results that can be reliable in the field of conservation, various analytical and examination methods have been applied such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FT-IR), and Laser-induced breakdown spectroscopy (LIBS). Prior to the elemental characterization of data samples, the local thermodynamic equilibrium (LTE) condition was established to guarantee the correctness of the LIBS analysis. The results revealed the high efficiency of using nano silica in the inorganic form (dispersed in 2-propanol) than the same material but in hybrid form (dispersed in Klucel E) in regard of absorption of the materials in the matrix and the final appearance of the samples surfaces.

НАУКОВІ ПЕРЕДПРОЄКТНІ ДОСЛІДЖЕННЯ ТА ФОРМУВАННЯ КОНЦЕПЦІЇ РЕСТАВРАЦІЇ АКТОВОЇ ЗАЛИ ГОЛОВНОГО КОРПУСУ НАЦІОНАЛЬНОГО УНІВЕРСИТЕТУ “ЛЬВІВСЬКА ПОЛІТЕХНІКА”

The article highlights the results of the first round of conservation works to return the lost image of the assembly hall (meeting hall of the great senate) – the main building of the oldest building of the university. The purpose of the works is to create the methodology basis to restore the wall painting and sculpture decoration of the hall, to return it to its original authentic appearance from 1880-1884. The decoration of the hall was realized in 1884 by the artist and architect Ivan Dolynskyi, according to the idea of the first rector, architect Julian Zahariewicz. However, the original artistic decoration of the assembly hall was lost in the subsequent periods after the First World War. The walls of the hall and decorative plastic were covered with new paint layers of a nondecorative nature. The first test studies in 2015 showed the possibility of removing layers and opening the original wall painting decoration. They also testified to the need for conservation and restoration works of the authentic wall painting decoration, which in some places had cracks, local losses, and unsatisfactory technical conditions (flaking from plaster). Complex scientific architectural and conservation studies of the interior of the assembly hall were carried out, including the performance of all necessary types of research – from archival searches to soundings in paint coatings and stucco, and laboratory analyzes of materials. Research has revealed the nature of layering and the different states of preservation of the authentic painting layer in all parts of the hall, at different levels of the walls and decor. As a result of research, it was established the possibility of cleaning all walls, decorative stucco, and sculptures by mechanical means. Due to the large volume, it was recommended to divide the cleaning and conservation works into several stages. According to the concept of the discussed and approved project, the following were recommended as the main methods and stages of restoration works: – mechanical cleaning of the entire wall plane; removal of paint coatings to the layer of authentic marbling; also removing putty from cracks and gaps in the plaster; – delicate wiping of the wall surface with distilled water to remove surface contamination; – injection of deep cracks with liquid restorative putty mass; – “bringing” plaster in places of losses, falls and chips, followed by its alignment in the plane of the wall and its priming; – strengthening of the places of the base where there are losses, shedding of the wall painting by the method of its structural strengthening with the help of impregnation with a special priming solution; – restoration reproduction and toning of the wall painting (exclusively within the limits of losses); – after the completion of the reproduction of the wall painting-marbling (when the toning has completely dried), applying a restoration wax-resin mastic to the entire surface of the wall; giving a gloss after the mastic has completely dried; if necessary, mastic can be re-applied on new layers of wall painting. In the article, we reveal the main results of the research work, as well as highlight the key positions of the conservation task and the conceptual project of conservation, and recommendations for planning executive works. We also reveal the process of implementation of conservation works at their first stage - in 2015-2016. The works were carried out by the restoration group of the Department of Architecture and Conservation with the involvement of students.

The use of environmentally friendly abrasive blasting media for paint removal from wood surfaces

This study determined some physical changes that occur on wood surfaces aged in a marine environment resulting from the removal of coatings using environmentally friendly media blasting. Scots pine (Pinus sylvestris L.) wood coated with water-borne and synthetic paints was exposed to a marine environment for 100 days. The aged paint layers were removed using five different media (sodium bicarbonate, hazelnut shell granules, corncob granules, walnut shell granules, and apricot kernel granules), varying blasting angles (45° and 90°), blasting distances (7 and 10 cm), air pressures (2 and 2.5 bar), and nozzle diameters (0.5 and 0.8 mm) using an automated blasting cabinet. The results showed that corn cob granules and sodium bicarbonate were less effective than other media for removing paint layers at the application parameters. The samples were tested for hardness, gloss, and total color change. Samples exhibited a remarkable total color change and gloss increase when the blasting distance was increased from 7 cm to 10 cm, while their hardness decreased. The highest gloss value was obtained on surfaces blasted with a nozzle diameter of 0.5 cm. Surfaces blasted with a nozzle diameter of 8 mm, however, yielded the highest total color change and hardest values.

INDIRECT INK TRANSFER FOR OFFSET PRINTING, TAKING INTO ACCOUNT THE ROUGHNESS OF THE OFFSET PRINTING PLATE SURFACE

This article is devoted to the study of the influence of the surface roughness of an offset printing plate on the form-decal contact and deckle-printed material. Taking into account the deepening of micro protrusions of the surface roughness of the printing plate into the body of the deckle, which lead to additional displacements and deformation of the deckle, the amount of ink on the surface of the form is determined. The separation and transition of the paint layer in the contact zone has been studied. It has been established that the ink layer located in the free space of the roughness of the surface of the printing plate is also involved in the transfer of ink. The proposed method of indirect ink transfer in offset printing allows you to determine more accurate values of consumables in the design of printing processes, also predict the quality of printed prints, determine the runtime of printing plates, and correctly configure the printing machine before the printing process.

Analysis of Chromate-based Primers for Protection of Aluminium Alloys on Historical Aircraft

ABSTRACT Immediately following the use of aluminium alloys, particularly Duralumin, in the construction of aircraft, protective coatings with anti-corrosion properties were developed. Among the numerous solutions to prevent corrosion, the most widely employed materials were organic primers containing chromates. This paper reports the study of the corrosion inhibitive compounds (chromates) used by aircraft manufacturers during World War II. More specifically, we have identified the nature of the compounds and assessed their current efficiency. Our analyses on samples collected from three different wrecks (French and German) excavated on terrestrial sites reveal that the primer contained either zinc tetroxychromate or lead chromate. Using XANES to study the chromium oxidation states elucidated the different phenomena taking place during the aging of the paint primer. We found that the reduction of Cr(VI) to Cr(III) species occurred either within the primer or at the interface of the primer with the Al alloy. This is believed to be due to alteration of the paint layer and its long exposure to the natural environment. However, even after 80 years, Cr(VI) is still present in the primers of these archaeological parts. Although a little altered, the chromate compound can still provide a source of inhibitor, thus maintaining the protection of the alloys.

Hydrogen Recovery from Waste Aluminum–Plastic Composites Treated with Alkaline Solution

An alternative solution to the problem of aluminum-plastic multilayer waste utilization was suggested. The process can be used for hydrogen generation and layer separation. Three different sorts of aluminum-plastic sandwich materials were treated with an alkali solution. In the temperature range of 50-70 °C, for tablet blisters of polyvinylchloride and aluminum (14.8 wt.%), the latter thoroughly reacted in 15-30 min. For sheets of paper, polyethylene, and aluminum (20 wt.%), full hydrogen 'recovery' from reacted aluminum component took 3-8 min. From the lids of polyethylene terephthalate, aluminum (60 wt.%), and painted polyethylene with perforations, the aluminum was consumed after 45-105 min. The effect of perforations was the reduction of the process duration from nearly 90 min for the lids with no perforations to nearly 45 min for the perforated ones (at 70 °C). Perforations provided better contact between the aluminum foil, isolated between the plastic layers, and the alkali solution. Hydrogen bubbles originating near those perforations provided foil separation from the upper painted plastic layer by creating gas gaps between them. The remaining components of the composite multilayer materials were separated and ready for further recycling.

Layer separation mapping and consolidation evaluation of a fifteenth century panel painting using terahertz time-domain imaging

Over time, artworks often sustain paint layer separation and air gaps within their internal structure due to storage conditions and past restoration efforts. Because of this, paint layer consolidation interventions are an essential activity for art conservators. However, it is difficult to determine the exact location and the extent of layer separation on a piece of art in a non-invasive way, and even more difficult to evaluate the success of a consolidation intervention. In this work, a fifteenth-century wood panel painting was analyzed using terahertz time-domain imaging before and after it was consolidated. Using the terahertz data, it was possible to determine the areas on the artwork in need of consolidation and aid the intervention. The analysis of the after data allowed for the control and determination of the success of the consolidation effort in a non-destructive manner.

Measuring Maritime Paint Thickness under Water Using THz Cross-Correlation Spectroscopy

The shipping industry is a major contributor to global greenhouse gas (GHG) emissions, which is why it is important to optimize every aspect of the efficiency of ocean-going vessels. This includes the antifouling paint that ensures hydrodynamic efficiency. Measuring the thickness of the antifouling on top of all other paint layers using THz cross-correlation spectroscopy (THz-CCS) underwater could enable vessel operators to monitor the state of the paint on ship hulls and plan any vessel’s sailing route and maintenance optimally. However, due to the high absorption of water in the THz domain, measuring through any significant amount of water is impossible, making a water removal method necessary. This study shows how a THz-CCS system can be packaged for underwater measurements using a molded silicone contact seal. In combination with a spectroscopic model for data treatment, the thickness of a single paint layer is retrieved underwater. This paves the way for a more advanced system capable of measuring multilayer maritime paint underwater, which will enable shipping companies to continuously monitor the paint layers’ thickness.

Towards low-temperature laser paint stripping by photochemical mechanism on CFRP substrates

Multilayer paint on the surfaces of carbon fiber-reinforced polymer (CFRP) composites was cleaned using an ultraviolet picosecond laser (λ = 355 nm) under different parameters. The surface morphology of the composite after paint removal was investigated by scanning electron microscopy (SEM), chemical composition and functional group detection by energy dispersive spectroscopy (EDS) and FT-IR, while the sample temperature was monitored by an infrared thermal imager during cleaning. Additionally, CFRP performances were evaluated before and after paint removal. These results demonstrated that after three cleaning cycles with 12 W laser power, the paint layers on CFRP is removed, the surface epoxy resin is retained, and the carbon fiber does not have any morphological damage. At the same time, the surface after de-painting also met the re-painting conditions, and the tensile strength was not degraded compared with the original sample. It is noteworthy that the UV picosecond laser shows “low temperature cleaning”, which completely removes the paint layer on the CFRP surface at a temperature below 80 °C. This means that the paint stripping process will not cause potential thermal damage or degradation of mechanical properties for CFRP. Mechanism analysis indicated that the photochemical action led to the breaking of the chemical bond of the paint, thus achieving paint removal. This study demonstrates the feasibility of a laser cleaning process for de-painting from resin-based composite surfaces and guides the repair and maintenance of commercial aircraft.

Co-pyrolysis of waste polyester enameled wires and polyvinyl chloride: Evolved products and pyrolysis mechanism analysis

Waste enameled copper wire is an important secondary source of copper and often recovered by removing their organic paint layer through pyrolysis. This research focused on studying co-pyrolysis behaviors of poly(ethylene terephthalate) (PET) paint of waste enameled wires, mixed with a small amount of polyvinyl chloride (PVC) which is part of electric wires or cables. The results indicated that mixing PVC with a mass fraction of 10% into enameled PET wire paint (EPET) would significantly affect pyrolysis products, especially the chlorinated compounds, as well as increase energy consumption of the pyrolysis process. TG-FTIR and Py-GC/MS analyses showed that the chlorinated organics were mainly generated in the second stage of pyrolysis. Chloroesters such as terephthalic acid, di(2-chloroethyl) ester were dominant over other chloroorganic compounds, and their formations were attributed to the addition reaction of aromatic vinyl esters with HCl which formed from PVC pyrolysis. It is also worth mentioning that the chemically active acid chlorides including propanoyl chloride and benzoyl chloride were detected in the products, and they were proposed to be formed from the HCl acidolysis of esters that produced from pyrolytic EPET. Besides pyrolysis products, energy consumption of pyrolysis process also was closely correlated to the interactions between pyrolytic PVC and EPET. The average co-pyrolysis activation energy was calculated by Kissinger-Akahira-Sunose (KAS) method and was about 15 kJ/mol higher than that of EPET. These should be consequences of reactions between HCl and EPET. Since PVC is the minority component in the pyrolysis mixture that HCl eliminated from the few PVC was mostly consumed by EPET to form chloroorganic compounds, which negatively influences EPET degradation.

Multi-analytical investigations on a tomb mural painting of the Yuan dynasty in Chongqing, China

In this study, we conducted diagnostic research on a precious Yuan dynasty tomb mural painting (A.D.1271–1368) excavated in Chongqing, 2005. To restore the painting, the painting technique and the artwork's preservation state were investigated through optical microscope (OM), portable X-ray fluorescence (p-XRF), micro-Raman spectroscopy (μ-Raman), macro-Fourier transform infrared spectroscopy (macro-FTIR), and X-ray powder diffraction (XRD) analyses. During this process, the coarse ground, fine ground and painting layer were characterized and analyzed. Experimental results show that the compositions of coarse ground are calcite and soil, while fine ground mainly consists of calcite and a few amounts of silicate. We also investigated and identified the pigments and binders used for the painting layers, which revealed that carbon black was used for the black pigment, cinnabar, red ochre and small amounts of red lead were used for the red pigments. To further investigate the distribution of materials in cross-sections with special attention to trace presented organic material, a FPA detector was used for imaging coupled with a large radius germanium crystal equipped attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. It has been found that the protein may be used as the binder and organic additive in mural painting. Our work enhances the understanding of the mural painting technique of the Yuan dynasty and also provides a reference for the future restoration work of paintings.